[sql] Import SQLite 3.17.0.

third_party/sqlite/src/src/btreeInt.h

 /*
 ** 2004 April 6
 **
 ** The author disclaims copyright to this source code.  In place of
 ** a legal notice, here is a blessing:
 **
 **    May you do good and not evil.
 **    May you find forgiveness for yourself and forgive others.
 **    May you share freely, never taking more than you give.
 **
@@ skipping 241 matching lines @@
 /*
 ** Page type flags.  An ORed combination of these flags appear as the
 ** first byte of on-disk image of every BTree page.
 */
 #define PTF_INTKEY    0x01
 #define PTF_ZERODATA  0x02
 #define PTF_LEAFDATA  0x04
 #define PTF_LEAF      0x08
 
 /*
-** As each page of the file is loaded into memory, an instance of the following
-** structure is appended and initialized to zero.  This structure stores
-** information about the page that is decoded from the raw file page.
+** An instance of this object stores information about each a single database
+** page that has been loaded into memory.  The information in this object
+** is derived from the raw on-disk page content.
 **
-** The pParent field points back to the parent page.  This allows us to
-** walk up the BTree from any leaf to the root.  Care must be taken to
-** unref() the parent page pointer when this page is no longer referenced.
-** The pageDestructor() routine handles that chore.
+** As each database page is loaded into memory, the pager allocats an
+** instance of this object and zeros the first 8 bytes.  (This is the
+** "extra" information associated with each page of the pager.)
 **
 ** Access to all fields of this structure is controlled by the mutex
 ** stored in MemPage.pBt->mutex.
 */
 struct MemPage {
   u8 isInit;           /* True if previously initialized. MUST BE FIRST! */
-  u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
+  u8 bBusy;            /* Prevent endless loops on corrupt database files */
   u8 intKey;           /* True if table b-trees.  False for index b-trees */
   u8 intKeyLeaf;       /* True if the leaf of an intKey table */
-  u8 noPayload;        /* True if internal intKey page (thus w/o data) */
+  Pgno pgno;           /* Page number for this page */
+  /* Only the first 8 bytes (above) are zeroed by pager.c when a new page
+  ** is allocated. All fields that follow must be initialized before use */
   u8 leaf;             /* True if a leaf page */
   u8 hdrOffset;        /* 100 for page 1.  0 otherwise */
   u8 childPtrSize;     /* 0 if leaf==1.  4 if leaf==0 */
   u8 max1bytePayload;  /* min(maxLocal,127) */
-  u8 bBusy;            /* Prevent endless loops on corrupt database files */
+  u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
   u16 maxLocal;        /* Copy of BtShared.maxLocal or BtShared.maxLeaf */
   u16 minLocal;        /* Copy of BtShared.minLocal or BtShared.minLeaf */
   u16 cellOffset;      /* Index in aData of first cell pointer */
   u16 nFree;           /* Number of free bytes on the page */
   u16 nCell;           /* Number of cells on this page, local and ovfl */
   u16 maskPage;        /* Mask for page offset */
-  u16 aiOvfl[5];       /* Insert the i-th overflow cell before the aiOvfl-th
+  u16 aiOvfl[4];       /* Insert the i-th overflow cell before the aiOvfl-th
                        ** non-overflow cell */
-  u8 *apOvfl[5];       /* Pointers to the body of overflow cells */
+  u8 *apOvfl[4];       /* Pointers to the body of overflow cells */
   BtShared *pBt;       /* Pointer to BtShared that this page is part of */
   u8 *aData;           /* Pointer to disk image of the page data */
   u8 *aDataEnd;        /* One byte past the end of usable data */
   u8 *aCellIdx;        /* The cell index area */
   u8 *aDataOfst;       /* Same as aData for leaves.  aData+4 for interior */
   DbPage *pDbPage;     /* Pager page handle */
   u16 (*xCellSize)(MemPage*,u8*);             /* cellSizePtr method */
   void (*xParseCell)(MemPage*,u8*,CellInfo*); /* btreeParseCell method */
-  Pgno pgno;           /* Page number for this page */
 };
 
 /*
-** The in-memory image of a disk page has the auxiliary information appended
-** to the end.  EXTRA_SIZE is the number of bytes of space needed to hold
-** that extra information.
-*/
-#define EXTRA_SIZE sizeof(MemPage)
-
-/*
 ** A linked list of the following structures is stored at BtShared.pLock.
 ** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor 
 ** is opened on the table with root page BtShared.iTable. Locks are removed
 ** from this list when a transaction is committed or rolled back, or when
 ** a btree handle is closed.
 */
 struct BtLock {
   Btree *pBtree;        /* Btree handle holding this lock */
   Pgno iTable;          /* Root page of table */
   u8 eLock;             /* READ_LOCK or WRITE_LOCK */
@@ skipping 369 matching lines @@
 #define get4byte sqlite3Get4byte
 #define put4byte sqlite3Put4byte
 
 /*
 ** get2byteAligned(), unlike get2byte(), requires that its argument point to a
 ** two-byte aligned address.  get2bytea() is only used for accessing the
 ** cell addresses in a btree header.
 */
 #if SQLITE_BYTEORDER==4321
 # define get2byteAligned(x)  (*(u16*)(x))
-#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
-    && GCC_VERSION>=4008000
+#elif SQLITE_BYTEORDER==1234 && GCC_VERSION>=4008000
 # define get2byteAligned(x)  __builtin_bswap16(*(u16*)(x))
-#elif SQLITE_BYTEORDER==1234 && !defined(SQLITE_DISABLE_INTRINSIC) \
-    && defined(_MSC_VER) && _MSC_VER>=1300
+#elif SQLITE_BYTEORDER==1234 && MSVC_VERSION>=1300
 # define get2byteAligned(x)  _byteswap_ushort(*(u16*)(x))
 #else
 # define get2byteAligned(x)  ((x)[0]<<8 | (x)[1])
 #endif